Ukraine's president made a surprise trip to a key city in south-eastern Ukraine as a ceasefire between Russian-backed rebels and Ukrainian troops appeared to be largely holding.
Seeking to rally national unity, President Petro Poroshenko was in Mariupol - a city under attack for days by Russian-backed separatists - and declared it would remain a part of Ukraine.
After a series of military defeats to rebel forces in the country's eastern regions, Ukraine signed a ceasefire deal on Friday that has been widely viewed at home as an act of capitulation. Much of the region has remained calm as the truce appeared to be holding, although sporadic unrest was reported.
"We will do everything to ensure there is peace, but we will also brace ourselves for the defence our country," Mr Poroshenko told metal workers at a plant that was within the range of the rebels' rockets.
His trip to Mariupol came days after it came under sustained shelling from rebels stationed along the 40-mile stretch between the strategic port on the Sea of Azov and the Russian border.
"This city was, is, and will be Ukrainian." he told the crowd.
The agreement reached in Minsk, the capital of Belarus, called for an immediate halt to fighting and an exchange of prisoners. It also called for the central government to give a greater degree of autonomy to the separatist Russian-speaking regions of Donetsk and Luhansk, although details remained vague.
While insisting the agreement would not lead to the break-up of Ukraine, Mr Poroshenko expressed some openness to further discussions on the shape of the country.
"I think that we should elect the real representatives of Donetsk and Luhansk. And we, with them, can negotiate anything, excluding the sovereignty of territorial integrity," he said.
But Mr Poroshenko peppered his conciliatory messages with a determination to repel what he strongly implied was Russia's aggression.
"Mariupol has proven that we won't let anybody burn our city to the ground. The workers of Mariupol have protected peace and calm in the city," he said.
He also announced that thousands of prisoners would be released by the rebels. He later announced that 20 Ukrainian soldiers had been freed.
Earlier the Kremlin said Mr Poroshenko and Russian President Vladimir Putin had spoken by telephone and "continued to discuss steps helping peaceful settlement in southeastern Ukraine".
The two leaders had also talked on Saturday about implementing the ceasefire plan in the conflict that has lasted nearly five months and killed at least 3,000, according to a UN estimate.
"The dialogue will continue," the Kremlin said.
Meanwhile, the European Council formally adopted a package of further sanctions against Russia but delayed enforcement to see if the ceasefire holds.
Council President Herman Van Rompuy said the sanctions will be implemented in the next few days, which would leave time for "an assessment of the implementation of the ceasefire agreement and the peace plan".